Whenever you compare home water purifiers, some are much better than others.

Technically, any system surpasses none, because anything is an improvement of tap-water, but my biggest personal concern is cancer.

Maybe that's yours, too.
No-one knows yet exactly what causes cancer.
They believe that there are multiple risk factors that could include genetic, diet, environmental factors and experience of toxins. lan shan water filter

Since, there seems to become a genetic risk in my family and I can't change my genes, I look for different ways to lessen my risks.

So, I compare home water purifiers on the basis of the cancer-causing chemicals they remove. One of the big ones is THMs.
THMs are trihalomethanes.

They are produced when chlorine is used for disinfection. If you compare home water purifiers, you will dsicover that many remove chlorine, but just a few remove THMs.
THMs can vaporize, as water can, so purification methods, such as for instance boiling and distillation, won't remove them.